Biology · Organisation. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
Cells are the building blocks of the body. A tissue is a group of cells with a similar structure and function. An organ is a group of different tissues working together, and organs work together in organ systems. The digestive system breaks food down and absorbs it.
Digestion depends on enzymes, which are proteins that speed up reactions. Each enzyme has an active site with a special shape. Only one substrate fits it, as a key fits a lock. Too high a temperature, or the wrong pH, changes the shape of the active site. The enzyme is then denatured and stops working.
Enzymes break large insoluble molecules into small soluble ones that can be absorbed into the blood.
Students write that heat kills an enzyme. Enzymes are not alive: say that the enzyme is denatured because the shape of its active site has changed.
Answer: Starch and protein, but no reducing sugar.
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